The cuticle of the nematode Caenorhabditis elegans is a multi-layered collagenous "skeleton' that plays crucial roles in both morphogenesis and motility. Because collagen is a major constituent of the cuticle, genetic analysis of cuticular morphology is useful in studying the structure and function of collagen molecules in vivo. The experiments in this proposal concentrate on analyzing the structure and assembly of one substructure within the cuticle, using the bli-1 and bli-2 genes. The cuticles of animals mutant in these genes are covered by fluid-filled blisters, which result from an apparent separation between cuticular layers. Animals mutant for bli-1 have been shown to lack structures referred to as "struts", which function to hold two cuticular sublayers together. The function of these struts may be analogous to the function of anchoring fibers in vertebrate skin; these collagenous structures bind together the dermis and epidermis. The experiments outlined in this proposal aim first to use a variety of genetic and molecular biological techniques to characterize the genomic sequences corresponding to these loci. The next steps in this outline attempt to analyze the loci in terms of RNA and protein expression patterns using molecular and immunological techniques as well as gene fusion studies in transgenic animals. These experiments will also further investigate the phenotype of animals mutant in bli-1 and bli-2 using genetic and ultrastructural analysis. The final set of experiments in this study are aimed at gaining an understanding of the morphogenesis of the struts using a combination of classical genetic techniques as well as transgenic animal technology.